This invention relates to lifts or elevators in general, and to wheelchair lifts for vehicles in particular.
In recent years, our society has become more conscious of the needs of handicapped persons, and a need has been recognized for means allowing persons who use wheelchairs to easily and safely board a vehicle such as a van or a bus. The prior art includes many examples of lifts or elevators which can be used for this purpose.
Many prior art wheelchair lifts utilize a platform which is designed to be pivotally swung or otherwise extended outwardly of the side of the vehicle and lowered to the ground or raised to the passenger floor level as desired, to allow a wheelchair passenger to embark into or disembark from the vehicle. To stow the platform when the lift is not in use, the platform is typically pivotally swung into a generally vertical position or slid or folded into some type of stowage area so that the lift mechanism does not protrude from the side of the vehicle, and to permit the door of the vehicle to be closed. A disadvantage of this type of lift is that once the wheelchair passenger is lifted to the passenger floor level, it becomes necessary for such passenger to be moved off the platform and into the vehicle before the platform can be stowed and the vehicle operated, and for the platform to be deployed and the wheelchair passenger moved out of the vehicle and onto the platform before such passenger can be lowered to the ground. In addition, the wheelchair passenger is generally left suspended for a time on an open platform some distance from the ground, which may cause apprehension or vertigo in the wheelchair passenger or affect the wheelchair passenger's dignity; and may pose some safety problems as well.
Most of such prior art lifts also provide a supporting structure, an operating mechanism or both which impinge into the interior of the vehicle, thus taking up precious room and introducing undesirable noises inside the vehicle; and in some cases, exposing passengers to operating parts of the lift mechanism. It would therefore be desirable to provide a platform which forms part of the floor of the vehicle and is not required to be extended outwardly of the vehicle, thus adding to the mental and physical security and safety of wheelchair passengers; and which does not require moving the wheelchair passenger off the platform and stowing the platform before the vehicle can be operated, nor require that the platform be deployed and the wheelchair passenger moved onto the platform before the passenger can be lowered to the ground.
One prior art wheelchair lift, shown in the "MC-9 Wheelchair Lift Operators Manual", describes a wheelchair lift for a vehicle in which the lift platform forms part of the floor of the vehicle when the platform is in its raised position, which does not need to be extended outwardly of the vehicle before the lift can be used, and which does not require moving the wheelchair passenger off of or onto the platform for loading or unloading, or during operation of the vehicle. Said reference also shows that such lift is enclosed on three sides in an elevator-type shaft, which enhances the wheelchair passenger's feelings of mental security and dignity, and also provides greater physical safety. A disadvantage of this prior art lift is that it requires for its structure and operation platform stabilizers, hydraulic cylinders and other hydraulic components and controls which project to a significant degree into the interior of the vehicle above the passenger floor, and which require padding or shrouding for passenger safety and to provide visual and sound barriers around said components. Such components not only take up valuable room and create unwanted noises inside the vehicle, but also make it more difficult for wheelchair and other passengers to maneuver within the vehicle. Also, the presence of such components inside the vehicle makes it necessary to dedicate more space inside the vehicle to the wheelchair lift, which might otherwise be occupied by ordinary passenger seats which can be used by non-handicapped passengers. This is a particular problem for vehicles such as buses used for public transportation, and only occasionally used by wheelchair passengers. Further, the use of a plurality of hydraulic cylinders in said lift requires hydraulic circuitry, controls. valves, pumps, and a hydraulic fluid reservoir of appropriate size and complexity to serve the needs of such a system, adding weight thereto, taking up space that might be used for other purposes, and making the system more costly to build and maintain than a simpler system.
It would therefore be very desirable to provide a wheelchair lift for a vehicle which has a lift platform that serves as part of the floor of the vehicle in its raised position and does not need to be extended outwardly of the vehicle in order to load or unload a wheelchair passenger, which provides ample visual and physical barriers around the lift platform during operation of the lift for wheelchair passenger comfort and safety, and which eliminates above-floor lift structures or lift operating mechanisms to preserve maximum interior room and passenger seating flexibility in the vehicle, to remove objectionable noises from the passenger compartment, and to reduce or eliminate the safety problems presented by passenger exposure to operating parts of the lift mechanism. It would also be desirable to provide such a wheelchair lift with a minimum of hydraulic components to reduce the complexity of the system and to make the system easier to maintain and repair, to minimize the space taken up by such components, and to reduce the cost to produce the lift.